Near field, full duplex data link for resonant induction wireless charging

ABSTRACT

A full duplex, low latency, near field data link controls a resonant induction, wireless power transfer system for recharging batteries. In an electric vehicle embodiment, an assembly is aligned with respect to a ground assembly to receive a charging signal. The vehicle assembly includes one or more charging coils and a first full duplex inductively coupled data communication system that communicates with a ground assembly including one or more charging coils and a second fill duplex inductively coupled data communications system. The charging coils of the ground assembly and the vehicle assembly are selectively enabled based on geometric positioning of the vehicle assembly relative to the ground assembly for charging. As appropriate, the transmit/receive system of the ground assembly and/or the vehicle assembly are adjusted to be of the same type to enable communication of charging management and control data between the ground assembly and the vehicle assembly during charging.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 16/570,801, filed Sep. 13, 2019, which is acontinuation-in-part of U.S. patent application Ser. No. 16/158,978,filed Oct. 12, 2018, which is a continuation of U.S. patent applicationSer. No. 15/508,611, filed Mar. 3, 2017, which is a U.S. National StageApplication filed under 35 U.S.C. 371 of International Application No.PCT/US2015/048521, filed Sep. 4, 2015, which claims priority to U.S.Provisional Patent Application No. 62/046,392, filed on Sep. 5, 2014.The contents of the referenced applications are hereby incorporated byreference.

TECHNICAL FIELD

A full duplex, near field data link intended for control of a resonantinduction, wireless power transfer system is used for rechargingelectric vehicles. A coherent transponder configuration enablesinterference rejecting synchronous detection and positive rejection ofsignals originating from nearby and adjacent vehicles.

BACKGROUND

inductive power transmission has many important applications spanningmany industries and markets. Resonant induction wireless power apparatusmay be viewed as a switch mode DC-to-DC power supply having a large airgap transformer separating and isolating the power supply input andoutput sections. Because the output current is controlled by adjustmentof the input side parameters, there must be a way to communicate theoutput parameters to the input side control circuitry. Conventional,isolated, switch mode power supplies use optocouplers or couplingtransformers to communicate across the isolation barrier but theseconventional methods are not useful in the presence of a large physicalgap. Acoustic and optical communications across the power transfer gapare possible in principle but are inadequate in practice when challengedby mud, road debris, snow and ice as well as standing water. It ispossible to communicate across the power transfer gap by means ofmodulating the receiving inductor impedance and detecting the voltageand current variations induced on the primary side inductor. However,because of the generally low operating frequency employed by theresonant induction wireless power transfer apparatus and the moderate tohigh loaded Q of the primary and secondary side inductors of suchresonant induction wireless power transfer systems, available datacommunications bandwidth is severely constrained and full duplexcommunications implementation is difficult.

Radio frequency-based data communications systems are thereforepreferred as they are immune to the difficulties listed above; however,conventional radio frequency data communications systems are inadequatein several aspects. Half-duplex systems transmit only in one directionbut rapidly alternate the direction of transmission, thereby creating adata link that functions as a full duplex link. Transmission databuffering or queueing introduces significant and variable transmissionlatency which is especially undesirable as a cause of control systeminstability when placed in the control system feedback path.

Conventional superheterodyne receivers generally require rather goodintermediate frequency filters to provide off-channel interferencerejection. However, such filters tend to be expensive and do not easilylend themselves to monolithic integration.

Furthermore, conventional radio data links do not intrinsicallydiscriminate against other nearby data links of the same type. Thismeans that conventional radio-based data links when employed to mediatewireless charging of electric vehicles often respond to the radiocommands emitted by charging apparatus in nearby or adjacent parkingslots, a behavior that greatly complicates unambiguous vehicleidentification and subsequent wireless charging control.

SUMMARY

The systems and methods described herein address the above and otherlimitations of the prior art by implementing a coherent, full-duplexradio frequency data link that relies upon near field inductive couplingas opposed to far field propagation as in conventional systems torestrict effective communication range, that employs synchronousdetection to reject off channel and some co-channel interference withoutsophisticated frequency domain filtering, and that employs a coherenttransponder architecture for positive identification of data linktransmission-reception equipment pairs.

In sample embodiments, two apparatuses are provided, one associated withthe ground side wireless power transmission equipment, and anotherassociated with the vehicle side wireless power reception equipment. Acrystal-controlled reference oscillator located in the ground sideapparatus provides a common basis for the coherent generation of allradio frequency signals needed for transmission and for detection. Asthis is a full duplex communication apparatus, there are two independenttransmission-reception links: a forward link from the ground side to thevehicle side apparatus, and a return link from the vehicle side to theground side apparatus. The vehicle side loop antennas are typicallylocated below the conductive underbody of the vehicle and are parallelwith respect to the ground surface.

The forward link transmission signal is derived from the referenceoscillator. Serial data is imposed upon the forward link carrier by themodulator. Transmission occurs between two electrically small loopantennas having significant mutual induction coupling that are separatedby much less than a wavelength at the forward link operating frequency.On the vehicle side of the forward link, the received signal is detectedby a homodyne detector that extracts the carrier of the signal and usesit as a detection reference in a synchronous detector. The extractedcarrier is multiplied in frequency and used as the carrier for thereturn link with the return link data imposed upon the carrier with asecond modulator. Return link transmission occurs by near field,inductive coupling between two closely spaced, electrically small loopantennas as before. A synchronous detector on the ground side of thelink extracts the return link data using a frequency multiplied versionof the original reference oscillator signal as the detection reference.Link modulation in both directions may be amplitude modulation, phasemodulation, or a combination of both.

Because the forward link carrier, the forward link detection reference,the return link carrier, and the return link detection reference are allderived from the same reference oscillator, coherency of these fourcritical signals is assured by design. Complex frequency acquisition andsynchronization circuitry is not required. Furthermore, productiontolerance and environmentally induced frequency variations betweenreference oscillators ensures that the link signals from apparatuslocated in adjacent parking spaces will not be coherent and thereforewill not be subject to synchronous detection. Further rejection of linksignals originating from apparatus and vehicles in adjacent parkingslots arises from attenuation that results when the link transmissionwavelength exceeds the vehicle underbody to ground surface separationdistance with the vehicle underbody and the ground surface functioningas the two plates of a waveguide operating below the guide propagationcutoff frequency.

In accordance with a first aspect, a charging system is provided thatincludes a first coil assembly comprising a charging coil and a firstfull duplex inductively coupled data communications system comprising afirst transmit/receive system that transmits a first signal over a firstinductive link and receives a second signal over a second inductivelink, and a second coil assembly comprising a charging coil and a secondfull duplex inductively coupled data communication system comprising asecond transmit/receive system that receives the first signal over thefirst inductive link and transmits the second signal over the secondinductive link. In sample embodiments, the first and secondtransmit/receive systems are adapted to be selectable among at least oneof hardware, software, and firmware configurations that are adapted tomodulate output signals and to demodulate input signals. Also, thecharging coil of the first coil assembly is configured to be disposed inparallel to the charging coil of the second coil assembly to receive acharging signal during charging and is selectively enabled to match ageometry of the second coil assembly during charging.

In sample embodiments, the first transmit/receive system comprises aprocessor that processes data from at least one of the first coilassembly and external systems for transmission to the second coilassembly and processes data received from the second coil assembly fordelivery to at least one of the first coil assembly and the externalsystems for processing. In the sample embodiments, when a failure eventis detected by the first coil assembly or received from the second coilassembly, the processor disables the charging signal.

In other sample embodiments, the second transmit/receive systemcomprises a processor that processes at least one of commands and datafrom the second coil assembly and from external systems for transmissionto the first coil assembly and processes data received from the firstcoil assembly for delivery to the second coil assembly and at least oneof the external systems. In the sample embodiments, the second coilassembly further comprises a digital interface and the processorprovides measurements related to the first signal, the second signal,and the charging signal to the digital interface. The measurementsinclude at least one of signal strength, bit-error-rate, ratio of Energyper Bit to a Spectral Noise Density, frequency, and amplitude and phaseshift at first and second antenna structures of the first coil assemblyand second coil assembly. In the sample embodiments, the externalsystems may comprise an external processor. In such embodiments, themeasurements are delivered via the digital interface to the externalprocessor for at least one of alignment detection and closed loopcharging system management and control. The external processor mayprovide near real-time voltage and current measurements on the secondcoil assembly, thermal measurements of the second coil assembly, Z-gapchanges, first coil assembly or second coil assembly failure alerts,alerts regarding mid-charging performance events, and additional sensingdata related to the second coil assembly to the processor fortransmission.

In other sample embodiments, the first signal and the second signal areconfigured as either narrowband or wideband signals depending on a stageof a charging cycle or whether a threshold of signal quality has beencrossed.

In still other sample embodiments, the first signal and the secondsignal are configured as an asynchronous spread spectrum signal. In suchembodiments, the first and second transmit/receive systems each maycomprise a direct sequence spread spectrum system that transmitscomplementary code sequences that allow for the first and secondtransmit/receive systems to distinguish between signals and co-channelinterference.

In sample embodiments, the hardware, software, and/or firmware areadapted to modulate the output signals using at least two of amplitudemodulation, phase modulation, frequency modulation, Orthogonal FrequencyDivision Multiplexing (OFDM), and spread spectrum techniques. The spreadspectrum techniques may comprise at least one of direct sequence spreadspectrum, Chirp Spread Spectrum (CSS), binary orthogonal keying (BOK),and frequency hopping.

In still further sample embodiments, the first and secondtransmit/receive systems each comprises a receiver, an analog to digitalconverter, a digital processor that processes data from at least one ofthe first coil assembly and external systems for transmission to thesecond coil assembly and processes data received from the second coilassembly for delivery to at least one of the first coil assembly and theexternal systems for processing, a digital to analog converter, and atransmitter. In the sample embodiments, the analog to digital converterand digital to analog converter are implemented as discrete integratedcircuits and the digital processor is implemented as a fieldprogrammable gate array. Also, the analog to digital converter, digitalprocessor, and digital to analog converter may be implemented asfirmware residing in an application-specific-integrated-circuit (ASIC).In the sample embodiments, the digital processor of eachtransmit/receive system processes input data for transmission andprocesses data received from the other transmit/receive system usingsoftware structures implemented on the digital processor. The first andsecond transmit receive systems may optionally include at least onebandpass filter.

In accordance with a second aspect, a method of charging a vehicle isprovided that includes positioning a vehicle assembly with respect to aground assembly so as to receive a charging signal, the vehicleassembly, comprising one or more charging coils, with each charging coilhaving a first full duplex inductively coupled data communication systemcomprising a first transmit/receive system that receives a first signalover a first inductive link and transmits a second signal over a secondinductive link, and the ground assembly comprising one or more chargingcoils, with each charging coil having a second full duplex inductivelycoupled data communications system comprising a second transmit/receivesystem that transmits the first signal over the first inductive link andreceives the second signal over the second inductive link. The chargingcoils of the ground assembly and the vehicle assembly are selectivelyenabled based on geometric positioning of the vehicle assembly relativeto the ground assembly for charging. At least one of the firsttransmit/receive system and the second transmit/receive system areselected to have a same type of hardware, software, and/or firmwareadapted to modulate output signals and to demodulate input signals in asame manner as the other of the first and second transmit/receivesystems. Charging management and control data are communicated betweenthe first and second transmit/receive systems over the first and secondinductive links during charging.

In sample embodiments, the first transmit/receive system and the secondtransmit/receive system are adapted to modulate the output signals usingat least two of amplitude modulation, phase modulation, frequencymodulation, Orthogonal Frequency Division Multiplexing (OFDM), andspread spectrum techniques. The spread spectrum techniques may includeat least one of direct sequence spread spectrum, Chirp Spread Spectrum(CSS), binary orthogonal keying (BOK), and frequency hopping.

In other sample embodiments, at least one of software updates,diagnostic or telemetry information, and passenger entertainmentservices data are communicated between the ground assembly and thevehicle assembly via the first and second inductive links duringcharging. The charging signal may be disabled when a failure event isdetected by the ground assembly or received from the vehicle assembly.

In other sample embodiments, the first transmit/receive system processesat least one of commands and data from the vehicle assembly and fromexternal systems for transmission to the ground assembly and processesdata received from the ground assembly for delivery to the vehicleassembly and at least one of the external systems. Measurements relatedto the first signal, the second signal, and the charging signal also maybe provided to a digital interface for processing. The measurements mayinclude at least one of signal strength, ratio of Energy per Bit to aSpectral Noise Density, frequency, and amplitude and phase shift atfirst and second antenna structures of the vehicle assembly and groundassembly. The measurements may be delivered via the digital interface toan external processor for at least one of alignment detection and closedloop charging system management and control.

In yet other sample embodiments, the method includes transmitting atleast one of near real-time voltage and current measurements on thevehicle assembly, thermal measurements of the vehicle assembly, Z-gapchanges due to loading or unloading of a vehicle containing the vehicleassembly, ground assembly or vehicle assembly failure alerts, alertsregarding mid-charging performance events, and additional sensing datarelated to the vehicle assembly from the vehicle assembly to the groundassembly.

In still further sample embodiments, the method includes configuring thefirst signal and the second signal as either narrowband or widebandsignals depending on a stage of a charging cycle or whether a thresholdof signal quality has been crossed.

In yet further sample embodiments, the method includes configuring thefirst signal and the second signal as an asynchronous spread spectrumsignal. Complementary code sequences may be transmitted between thefirst and second transmit/receive systems that allow for the first andsecond transmit/receive systems to distinguish between signals andco-channel interference.

In accordance with a third aspect, a vehicle charging system is providedthat includes a clustered ground assembly comprising at least twoindependent coils, each coil having a first full duplex inductivelycoupled data communications system comprising a transmit/receive systemthat transmits a first signal over a first inductive link and receives asecond signal from a vehicle over a second inductive link, the first andsecond signals being communicated between the clustered ground assemblyand the vehicle during charging of the vehicle. The clustered groundassembly may include individual ground assemblies installed in a tight,contiguous fashion to form a single, macro ground assembly.

In sample embodiments, the vehicle being charged has two or more vehicleassemblies mounted to allow higher power transfer than may be achievedwith a single vehicle assembly and the clustered ground assembly,includes coils configured to match a geometry of the two or more vehicleassemblies.

In further sample embodiments, the vehicle being charged may be equippedwith a clustered vehicle assembly in a matching geometry to theclustered ground assembly. The clustered vehicle assembly may compriseat least two independent coils, each coil having a second full duplexinductively coupled data communications system comprising atransmit/receive system that transmits the second signal over secondinductive link and receives the first signal from the clustered groundassembly over the first inductive link, the first and second signalsbeing communicated between the clustered ground assembly and theclustered vehicle assembly during charging of the vehicle.

The clustered vehicle assembly and the clustered ground assembly mayeach include two or more functionally identical assemblies, eachfunctionally identical assembly including a magnetic induction antennaand a common resonant induction coil unit.

DETAILED DESCRIPTION OF THE DRAWINGS

The foregoing and other beneficial features and advantages of theinvention will become apparent from the following detailed descriptionin connection with the attached figures, of which:

FIG. 1 shows a conceptual representation of sample embodiments of groundside and vehicle side transmission equipment.

FIG. 2 shows a sample embodiment of a full-duplex radio frequency datalink.

FIG. 3 shows the low harmonic waveform employed by the sample embodimentof FIG. 2 to avoid self-interference.

FIG. 4 shows a representation of digital amplitude shift modulation usedby the sample embodiment of FIG. 2.

FIG. 5 shows an embodiment of the low harmonic generation circuit thatproduces the waveform shown in FIG. 3,

FIG. 6 shows a representation of digital amplitude shift modulation usedby the embodiment of FIG. 2.

FIG. 7 shows an embodiment of receiver level detection circuits.

FIG. 8 shows an embodiment of an apparatus for self-interferencecancellation.

FIG. 9 illustrates an embodiment of dynamic charging using thecommunications methodology described herein.

FIG. 10 illustrates an example of a clustered deployment of transmissionequipment in a sample embodiment.

FIG. 11a illustrates the signaling and components used by the WirelessPower Transfer (WPT) system's inductively coupled communications system(ICCS) in sample embodiments.

FIG. 11b shows an example of diversity receiver antennas for theWireless Power Transfer (WPT) system's inductively coupledcommunications system (ICCS).

FIG. 12a illustrates the functional elements of the ICCS in sampleembodiments.

FIG. 12b illustrates a sample hardware embodiment of the ICCS includingthe vehicle side assembly and the ground side assembly.

FIG. 13a illustrates an overhead view of a parking lot based wirelesscharging station deployed in a single-row geographic arrangement in asample embodiment.

FIG. 13b illustrates an overhead view of a parking lot based wirelesscharging station deployed in a double-row geographic arrangement in asample embodiment.

FIG. 14 illustrates an example of a highway enabled for dynamic chargingin sample embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Sample embodiments will be described with respect to FIGS. 1-14 for usein charging electrically powered vehicles, although those skilled in theart will appreciate that the teachings provided herein may be used inother non-vehicular resonant magnetic induction wireless power transfersystems. Such embodiments are intended to be within the scope of thepresent disclosure.

FIG. 1 illustrates a conceptual representation of sample embodimentswhere two apparatuses are provided, a ground side apparatus associatedwith the ground side wireless power transmission equipment, and avehicle side apparatus associated with the vehicle side wireless powerreception equipment. The data link illustrated in FIG. 1 may, forexample, be implemented in the coil alignment error detecting apparatusdescribed in U.S. Pat. No. 10,193,400. As shown in FIG. 1, the groundside apparatus includes a frequency multiplier 10, a data modulator 20that receives input data for transmission, and a synchronous detector 30that receives data on a return link from the vehicle side apparatus andprovides output data. Similarly, the vehicle side apparatus includes afrequency multiplier 40, a homodyne detector 50 that receives data on aforward link from the ground side apparatus, and a modulator 60 thattransmits data on the return link to the ground side apparatus. Loopantennas 70 and 70′ of the ground side apparatus communicate wirelesslyby induction with loop antennas 80 and 80′ on the vehicle side apparatusin a conventional manner. A crystal controlled reference oscillator 90located in the ground side apparatus provides a common basis for thecoherent generation of all radio frequency signals needed fortransmission and for detection. As this is a full duplex communicationapparatus, there are two independent transmission-reception links: aforward link from the ground side to the vehicle side apparatus, and areturn link from the vehicle side to the ground side apparatus. Thevehicle side loop antennas 80 and 80′ are typically located below theconductive underbody of the vehicle and are parallel with respect to theground side loop antennas 70 and 70′.

The systems and methods described herein and shown in FIG. 1 depart fromconventional radio data communications as follows:

-   -   The communications path is full duplex and bi-directional having        a forward path from the ground side apparatus to the vehicle        side apparatus and a second return data path originating with        the vehicle side apparatus sending data to the ground side        apparatus.    -   The electronic communication mechanism is near field, magnetic        field coupling between two antennas 70, 80 and 70′, 80′        sensitive to impinging magnetic field energy, rather than far        field, free space propagation of conventional practice radio        frequency data communications.    -   The forward path signal carrier provides the basis for the        generation of the secondary path signal by means of frequency        multiplication. This means that the secondary path signal is        harmonically related to the forward path signal and the        technical difficulty of deriving a synchronous and coherent        reference signal for return path synchronous detection is        avoided. Furthermore, the coherent, harmonically related        forward, return path signals make possible simple, unambiguous        rejection of co-channel and off channel-interference and        rejection of data link signals originating from other identical        apparatus in adjacent parking slots.

In the exemplary embodiment shown in FIG. 2, the forward path frequencyfrom reference oscillator 90 is 13.560 MHz. The return path operates onthe third harmonic of the forward path, 40.680 MHz. Both frequencies areinternationally allocated for non-communications Industrial, Scientificand Medical (ISM) use. Communications use is also permitted in ISMchannels with reduced regulatory requirements but interference isaccepted from all other ISM channel users. The non-radiating, near fieldnature of the coherent transponder system described herein along withthe waveguide below cutoff structure comprised by the vehicle conductiveunderbody and the ground surface in a typical application makes thedescribed system very tolerant of co-channel interference and for thisreason is well suited for use on ISM assigned frequencies.

The forward path signal generation begins with reference quartz crystaloscillator 90 operating at a frequency of 13.560 MHz. This signal isapplied to a waveform generation stage including 3^(rd) harmoniccancellation circuit 22 and amplitude shift modulator 24 that togethercomprise the modulator 20 of FIG. 1. Of course, other types ofmodulators, such as frequency shift modulators, QPSK modulators, and thelike may be used. In the exemplary embodiment, amplitude shift modulator24 generates the rectangular waveform shown in FIG. 3 where T is thewaveform period and the 3rd harmonic power is approximately zero. Asmall loop antenna 70 with a balanced feed serves as the forward pathtransmit antenna, while a second, vehicle mounted, balanced feed, smallloop antenna 80 is used for the forward path receive antenna. Bothantennas 70, 80 are much smaller than a wavelength at the operatingfrequency and for this reason are poor free-space radiators. However,when in close physical proximity, the two small loop antennas 70, 80have significant mutual magnetic field coupling that enables bothforward and reverse communications paths without significant free spacepropagation.

From the “Engineering Mathematics Handbook, Third Edition, Tuma, Jan J.,McGraw-Hill 1987 ISBN 0-07-065443-3, the Fourier series coefficients forthe modified sine waveform shown in FIG. 3 are given by:

$\beta_{n} = \frac{4{Sin}\frac{n}{3}\pi\;{Sin}\frac{n}{2}\pi}{n\;\pi}$Of the first twenty Fourier series coefficients, all but six are zero.The non-zero coefficients are the 5^(th) and 7^(th), which aresuppressed −14 dB and −16.9 dB, the 11^(th) and 13^(th) which aresuppressed −20.8 dB and −22.3 dB, and the 17^(th) and 19^(th) which aresuppressed −22.9 and −25.5 dB with respect to the desired n=1 component.While a mathematically ideal waveform has infinite third harmonicsuppression, a practical implementation will have less than infiniteharmonic cancellation due to non-equal 0-1 and 1-0 logic propagationdelays and from other small waveform asymmetries. Even so, the waveformof FIG. 3 generated by the 3^(rd) harmonic cancellation circuit 22 withthe circuit shown in FIG. 5 has excellent third harmonic suppression(3^(rd) harmonic energy approaching zero), a highly desirable feature toavoid self-interference between the third harmonic of the forwardtransmission path and detection of the 40.680 MHz return path. Remainingresidual third harmonic energy may be further suppressed, if necessary,using conventional harmonic filtering techniques.

The low third harmonic generation circuit shown in FIG. 5 consists of awalking ring counter comprised of three D flip-flops 102, 104, 106clocked at six times the desired output frequency as derived from the13.560 MHz frequency from the reference oscillator 90 by PLL frequencymultiplier 108. A pair of NAND gates 110, 112 decodes the walking ringcounter to produce the desired rectangular wave that drives the forwardlink loop antenna 70 by means of two transistors 114, 116 arranged in asymmetrical, push-pull configuration. The inductance of the two radiofrequency chokes 118, 120 connected to voltage source 122, combined withthe inductance of the loop antenna 70 and the antenna resonatingcapacitor 124 shown in FIG. 5, constitute a resonant circuit thatprovides suppression of residual harmonic energy, particularly thirdharmonics in the illustrated embodiment.

As shown in FIG. 2, in an exemplary embodiment amplitude shift keying(ASK) modulation is imposed upon the forward link carrier by amplitudeshift modulator 24 by varying the value of the forward link transmittingstage supply voltage. Logic one bits are encoded as full signalamplitude with the transmitting stage operating from full supplyvoltage. Logic zero bits are encoded as one half of the full signalamplitude with the transmitting stage operating with a reduced supplyvoltage. Varying the transmitter stage supply voltage in this fashionproduces the transmission waveform shown in FIG. 4.

On the vehicle side of the forward link, a variable gain controlledamplifier 52 increases received signal amplitude from loop antenna 80.Since the received signal has non-zero values even for logic zero bits,the 13.56 MHz carrier is always present (see FIG. 4). A portion of theamplified, received signal is applied to a limiting amplifier 54 thatremoves received signal amplitude variations, both those introduced byamplitude data modulation and those occurring due to incidental changesin the magnetic field coupling between the two forward path loopantennas 70, 80. The output of the limiting amplifier 54 is a constantamplitude square wave that indicates the instantaneous polarity of thereceived signal. The portion of the variable gain amplifier output notapplied to the limiting amplifier 54 is applied to one input of themultiplicative mixer 56. The limiting amplifier 54 output drives theother mixer input. The limiting amplifier 54 and the mixer 56 comprisethe homodyne detector 50 in which the incoming signal carrier isextracted and used to synchronously detect the incoming signal. Thepropagation delay of the limiting amplifier 54 is negligible orcompensated for to achieve the full advantages of coherent detection.The output of the homodyne detector 50 is equivalent to full waverectification of the incoming amplitude modulated signal.Resistor-capacitor low pass filtering removes the twice carrierfrequency ripple leaving a direct current voltage that varies amplitudeaccording to the impressed serial digital modulation. The carrier ripplefiltered, post-homodyne detector signal is applied to a level detectioncircuit 59 that feeds the automatic gain control (AGC) control loop 58and that also extracts the forward path serial data by means ofamplitude level detection. Its implementation will be described ingreater detail below with respect to FIG. 7.

The forward path carrier recovered by the limiting amplifier 54 isapplied to a frequency tripler 42 implemented as a pulse generatorfollowed by a filter or equivalently by a phase locked loop after firsthaving passed through a crystal filter 44 that prohibits frequencymultiplier operation except in the presence of a sufficiently strongforward link signal, thus avoiding conflicting frequencies. Theresulting 40.680 MHz carrier is applied to a second amplitude shiftmodulator 62 using 100% and 50% modulations levels as before to encodeserial, digital data on the return data path. The return path amplitudeshift modulator 62 drives a small, resonant loop antenna 80′ as beforeexcept that elements 102-112 of FIG. 5 are not needed.

On the ground side of the return link, there is a small resonant loopreceiving antenna 70′ and an amplifier 32 controlled by automatic gaincontrol (AGC) circuit 34. Synchronous detection of the received returnpath signal is implemented by generating a 40.680 MHz synchronousdetection reference signal by means of frequency tripling. While thefrequency error of the synchronous detection reference signal isguaranteed to be zero by the overall design of the apparatus, zero phaseerror is not assured and is obtained through the use of quadraturechannel phase detection and phase lock loop control of a phase shifterstage. Putting the phase shift stage (phase shifter 12) before ratherthan after frequency tripler 14 means total phase shift control rangeneed only exceed 120 degrees rather than the full 360 degrees requiredat the synchronous detector 30 to insure phase synchronous detection. Toease the quadrature reference signal generation at 40.680 MHz, theground side 13.560 MHz signal from the crystal oscillator 90 ismultiplied by frequency tripler 14 which outputs two square waves offsetby 90°. The frequency tripler 14 is implemented by a factor of six phaselocked loop frequency multiplier followed by a quadrature divide by twocircuit as shown in FIG. 6 including D flip-flops 130, 132 to obtain Iand Q synchronous detection reference signals. It will be appreciatedthat when the Q channel signal output at 17 equals 0V then there is nophase error. However, if the output at 17 is not 0V, then there is phaseerror and the phase lock loop operation of phase shifter 12 functions todrive the phase difference to zero.

The variable phase shift circuit 12 is implemented as a series ofcapacitively loaded, logic inverters with variable supply voltage. Thecapacitive loading increases the propagation delay from inverter inputto inverter output. Increased supply voltage decreases inverterpropagation delay, thereby reducing inverter phase shift. A conventionalphase locked loop comprised by the Q channel mixer 17 and associatedloop filter 16 drives Q channel output of the synchronous detector 30 tozero thereby insuring proper phase synchronization for the I channelamplitude detection.

The I channel mixer 38 of the synchronous detector 36 mixes the outputof amplifier 32 with the I channel output of frequency tripler 14,thereby providing the input signal for the level detection circuit 36.Forward path, level detection circuit 59 on the vehicle side isidentical to the return path, level detection circuit 36 on the groundside with the exception that the former includes the carrier detectionfunction and associated voltage comparator 138 (FIG. 7) which detectsthe presence of the return path signal.

FIG. 7 shows an embodiment of the receiver level detection circuit 36. Apeak hold capacitor 134 driven by a full wave precision rectifier 136holds the maximum detected voltage level which, in turn, is held to aconstant value by the AGC circuit 34 (FIG. 2). The AGC amplitudestabilized, peak detected voltage provides the reference voltage for the1-0 serial, binary detection voltage comparator 138 and the referencevoltage for the carrier detection voltage comparator 140 by means of aR-2R-R resistor voltage divider 142 that sets the voltage comparatorreference voltages at 25% and 75% respectively of the peak value of thepost detection waveform shown in FIG. 4. The carrier detection voltagecomparator 140 provides fast indication of vehicle side faultoccurrence. If a fault occurs on the vehicle side, such as suddenunexpected load shedding, the return link carrier is disabledimmediately. The ground side apparatus detects the carrier removaldelayed only by pre- and post-detection filter delay and immediatelyhalts wireless power transfer. The full value of the peak hold functionis applied to the AGC integrator 144 that adjusts the gain of the AGCamplifier 34 and thus the gain of amplifier 32 to maintain the peak holdcapacitor 134 voltage equal to the AGC set point 146 voltage. Theconventional precision rectifier 136 generates an output voltageproportional to the absolute value of the input voltage and consists ofone or more small signal diodes placed within an op-amp feedback path, aconfiguration that effectively cancels the diode forward voltage dropthereby enabling precision rectification of low level signals withminimal error.

Alternatively, return link synchronous detection may be made by makinguse of a coherent, but not phase synchronized, I and Q detectionchannels. Amplitude and phase modulation may be extracted in theconventional fashion where amplitude is the root mean square of the Iand Q channels and the phase angle is the arctangent of the ratio of Iand Q. In this alternative embodiment, the phase shifting and phaselocking circuitry is not needed.

FIGS. 1 and 2 show four loop antennas: a sending and a receiving antennapair 70, 80 for the forward link and a second pair of antennas 70′, 80′for the return link. In an alternative embodiment, the forward andreturn link antenna pair may be consolidated into a single loop antennawith a conventional antenna duplexer to separate and isolate the forwardand return link signals. Likewise, it is also possible to multiplex oneor both data link signals onto the wireless power transfer coils or ontoauxiliary electromagnetic structures such as the eddy current generationcoils that are part of the coil alignment error detecting apparatusdescribed in U.S. Pat. No. 10,193,400.

For reasons of simplicity and cost reduction, it is desirable that theforward and reverse paths share a common antenna structure. The problemthen is the combination and subsequent separation of the forward pathand the reverse path signal from each other and from other electricalsignals encountered by combining functionality into a single antennastructure. In general, there are two general methods to implement signalcombination, separation and routing. The first method uses hybridtransformers, hybrid couplers, or directional couplers which distinguishbetween forward and reverse path signals by means of signal flowdirection. The second method relies upon frequency selective filtersthat distinguish between signals on the basis of frequency. A frequencyselective multiplexer may be implemented with LC lumped components, withdistributed components or as a monolithic circuit containing a pluralityof resonant elements and coupling elements. A frequency multiplexingfunctional block may combine both signal direction and signal frequencydiscrimination.

The performance of a signal multiplexer functional block (circuit) maybe enhanced by the addition of electronic signal cancellation as shownin FIG. 8. The electronic signal cancellation functional block (circuit)is placed in the path between the common forward/reverse path antennaand the receiver. The common antenna is connected to port 202 of signalsplitter 204. One splitter output goes to the input port of mixer 206 bymeans of isolation amplifier 208. A sample of the signal to be cancelledis applied to port 210, and the applied signal is shifted in phase byvariable phase shifter 212 and applied to the local oscillator port ofmixer 206 by means of limiting amplifier 214. The mixer 206 output isapplied to a loop filter 216 and then applied to the control port of thevariable phase shifter 212. Components 212, 214, 206, and 216 constitutea phase control loop that insures the cancellation signal is 90 degreesout of phase with the unwanted signal component applied to port 202.Zero phase error corresponds to zero direct current voltage at theoutput of mixer 206.

As illustrated in FIG. 8, a second output of splitter 204 goes tocombiner 218 by means of isolation amplifier 220. As illustrated, signalcombiner 218, splitter 222, isolation amplifier 224, mixer 226, loopfilter 228, and attenuator 230 together constitute an amplitude controlloop. A portion of the quadrature sample signal output by phase shifter212 is applied to the fixed 90 degree phase shifter 232 creating a 180degree out-of-phase version of the cancellation signal, which passesthrough controlled attenuator 230 and into signal combiner 218, where ifthe cancellation signal amplitude is correct, complete cancellation ofthe unwanted signal is accomplished. One portion of the combiner 218output signal is directed to the receiver input at 234 via splitter 222.Another portion is directed through isolation amplifier 224 to thesignal port of mixer 226 which serves as a coherent amplitude detectordriven by an unattenuated portion of the 180 degree out-of-phasecancellation signal. The output of mixer 226 is passed through loopfilter 228 that controls the variable attenuator 230. Those skilled inthe art will appreciate that zero cancellation signal amplitude errorcorresponds to zero direct current voltage at the output of mixer 226.

In operation, as a vehicle approaches a wireless charging station,communications is established before charging commences. Once chargingcommences, the full-duplex communications is used to mediate and tocontrol multiple aspects of the wireless power transfer operationincluding transferred power level, output voltage and current, as wellas monitoring of proper system operation. To establish controlcommunications, the ground equipment may continuously or periodicallyemit a forward path signal while listening for a vehicle generatedreturn path signal. Duplex communication is initiated upon detection ofa vehicle generated return path signal. Alternatively, the vehicle sideelectronics may make initial contact with a return path signaltemporarily derived from a temporary crystal oscillator (not shown)instead of the normally used carrier recovered by the homodyne detector50, and non-coherently detected by the ground side electronics. Uponground side reception of the vehicle signal, the ground side equipmentemits a forward path signal. In the case of vehicle side communicationinitiation, the vehicle side apparatus disables the temporary crystaloscillator and reverts to coherent transponder operation upon successfulhomodyne detection and carrier recovery.

Both initiation methods described above rely upon the emission of aforward or a return path signal. Communications also may beadvantageously initiated with no forward or reverse path emissions. Inan exemplary embodiment, the ground equipment detects the change causedby an overhead vehicle in the impedance of the wireless power transfercoil and responds by emitting a forward path signal. This embodimentreduces or eliminates unnecessary signal emissions and is advantageousin some regulatory environments. In addition to the wireless powertransfer coils, the initiating impedance change also may be detected inthe coil alignment auxiliary coils or in the near field communicationsantenna. In addition to impedance change, changes in mutual impedancebetween isolated electromagnetic elements also may be used to initiatecommunications.

In the exemplary embodiment described herein, the reverse signal at40.680 MHz is a simple integer multiple of the forward signal frequencyat 13.560 MHz with both signals falling within existing, internationallydesignated ISM—Industrial, Scientific Medical—frequency assignments.Other frequencies and frequency pairs with non-integer frequency ratiosmay be used as well. For example, the two international ISM frequencybands with center frequencies of 2450 MHz and 5800 MHz may also be used.The coherent transponder architecture described herein combined withconventional phase locked loop techniques may generate a 5800 MHz signalthat is frequency synchronized with a 2450 MHz signal with a frequencyratio M/N of 116/49, where M=5800 MHz and N=2450 MHz. Other combinationsof ISM bands and non-ISM band frequencies, frequency pairs with otherinteger or rational fraction frequency and multiple simultaneoustransmission and reception carrier frequencies are also possible. Forexample, multiple return path data channels, each return path datachannel transmitting data at a different M/N multiple of thetransmission frequency of the first inductive link, where M and N areintegers, may also be used. Full duplex, frequency coherentcommunications is also possible with the ground and the remote apparatuslinked by far field as opposed to near field propagation.

Dynamic Charging

Dynamic electric vehicle charging is a specialized case of providingelectrical energy to an electrically powered vehicle while the vehicleis in motion. As illustrated in FIG. 9, the use of dynamic charging maybe accomplished using resonant magnetic induction in which a pluralityof independent transmitters 300 are installed in a roadway in a lineararray and energized in a controlled sequence as a target vehicle 310,312 travels above the linear array 300. Dynamic charging may beimplemented when there is just one vehicle 310 moving over the array oftransmitters 300, or in the more realistic circumstance, when there aremultiple electric vehicles 310, 312 of differing types, velocities, andpower requirements moving over the array of transmitters 300. In thelatter case, the sequencing of the energization of specific transmitters300 will be variable within the array and will depend on the variousvehicle types and their motion, factors which are inherentlyunpredictable. Thus, the technology requirements of dynamic chargingpose special technical challenges. The system described above solves themultiple problems of dynamic charging as enumerated below.

The most acute problem for dynamic charging is the need forvehicle-to-ground and ground-to-vehicle communications, where discrete,high speed, highly discriminatory and reliable data is transferred as arequirement for commanding and controlling the charging system. Thisdata is required to operate the charging system in the case of one orseveral vehicles that may traverse a serial array of ground-embeddedinductive power transmitters.

As shown in FIG. 9, an array of inductive power transmitters 300 isinstalled below a roadway, each transmitter 300 placed in a serial arrayalong the longitudinal axis of the roadway. The intent is to provide alength of roadway that, when driven over by an electrically poweredvehicle 310, 312, may supply electrical energy to the vehicle 310, 312traveling over the linear array of inductive transmitters 300. It isdesirable that only the transmitters 300 that are directly underneaththe vehicle receiver be energized. The transmitters 300 that do not havea vehicle above them should remain inert (i.e., not energized).

In every instance of inductive power transmission, whether in thedynamic charging mode described here, or in the simpler case ofstationary charging described above where a vehicle that is equippedwith a single power receiver is parked and remains immobile above asingle power transmitter that is embedded in the pavement, communicationbetween the vehicle-based receiver and the ground-based transmitteroccur. This is desirable for vehicle identification, billing for energypurchases, regulating current and voltage, resonant frequency, verticalgap separation distance, primary-to-secondary alignment, and for otherpurposes, such as safe operations and emergency power cut-off. This isalso true in the case of a moving vehicle that is charging while it isin motion, except that the single transmitter built into the vehiclecommunicates with a plurality of independent transmitters in sequence.This moving one-to-one relationship imposes very significantcommunications challenges.

The method of operation for charging a moving vehicle is to have eachindependent transmitter 300 in the linear array energize to create aresonant magnetic field in a sequential pattern as the vehicle receiver320 passes over each independent transmitter 300. The type of vehicle,its specific charging requirements, its velocity, alignment with respectto the transmitter 300, and its predicted trajectory are all importantfactors that make this problem difficult to solve.

As depicted in FIG. 9, it is certain to be the case that an array ofpavement-embedded transmitters 300 will experience the presence of twoor more vehicles 310, 312 simultaneously and respond to the variableconditions of each vehicle 310, 312. In this case, communicationsbetween each vehicle 310, 312 and the specific ground transmitter 300over which it is positioned is discrete and discriminatory so that noother vehicle 310, 312 is confused or data transmissions from a nearbyvehicle 310, 312 are received and misread. The requirements for thisinclude that the data communications system be proximally constrained tothe target area of the intended vehicle 310, 312. By comparison,broadcast radio and other systems such as Wi-Fi have a range that mayeasily be received by many nearby vehicles.

The first requirement is to have a highly proximal send-receivecapability that is limited to less than 2 meters. (A vehicle moving at60 MPH travels 88 feet per second. The time of exposure of the receiverto the transmitter may be on the order of 0.02 seconds. In thistimeframe, a time delay in the signal transmission typical of digitalcommunications systems of 0.04 to 0.07 seconds is clearly untenable).

The second requirement is to have no or very low time delay (or latency)in the signal. This is required because the vehicles 310, 312 may bemoving at high rates of speed over the plurality of transmitters 300,and discrete communications between the onboard receiver 320 and any onetransmitter 300 should be assured.

The third requirement is for the communications system to be able to“hand-off” or sequence the communications to the sequenced array oftransmitters 300. This may be done by wiring the transmitters 300 toeach other, or by allowing one transmitter 300 to communicate using thenear field communication system described herein to address the adjacenttransmitter 300 in the sequenced array.

The fourth requirement is for full duplex operation, orbidirectionality, so as to assure that in the very short time span thatthe vehicle 310, 312 is present over the transmitter 300, data may beexchanged in both directions—from the vehicle to the ground, and fromthe ground to the vehicle.

The fifth requirement is to allow uninterrupted communications under allweather and environmental conditions. This is accomplished by usingmagnetic energy, as described herein, which allows communication throughbodies of water, snow, ice, and other inclement road surface conditions.

The sixth requirement is to avoid the problem of multiple antennas thatare distal to the vehicle 310, 312. Multiple distal antennas introducesignificant problems due to road pavement and vehicle body interference,such as multipath signal nullification. High reliability vehicleidentification with multiple antennas is difficult to secure to avoidmalicious hacking or other cyber-vandalism.

Those skilled in the art will appreciate that the communication systemdescribed herein offers a uniform solution to each of theserequirements.

As noted above, dynamic charging allows moving vehicles to be chargedwhile driving as the vehicles 310, 312 pass over transmitters 300 in theroadway. Each transmitter 300 is energized in a controlled sequence asit anticipates the presence of a vehicle 310, 312 above it. Since thevehicle receiver 320 is only “present” above any one charging stationfor a short time, a sequencing system is needed that knows where thevehicle's receiver and the charging station's transmitter are inrelation to each other in real-time. Ideally, a pre-sequence firingprocedure effectively establishes a traveling wave of magnetic energythat moves at the same rate as the vehicle receiver 320. In order to dothis, a communication system with minimal latency, such as thatdescribed herein, is needed. As noted above, the communication systemdescribed herein is very fast (near-zero latency) and very proximal, sothat where the receiver 320 is relative to a transmitter 300 is known.Thus, to enable dynamic charging, a series of charging stations equippedwith the communications system described herein is provided. Duringoperation, each charging station and/or vehicle transmitter providesinformation including, for example, vehicle identification, billing forenergy purchases, regulating current and voltage, resonant frequency,vertical gap separation distance, primary-to-secondary alignment, andfor other purposes, such as safe operations and emergency power cut-off,location, timing, trajectory, and/or speed information regarding thevehicle 310, 312 to the next transmitter so that the next transmitterfires when the vehicle's wireless charging receiver 320 is positionedover the transmitter 300 during travel.

Robust Hybrid Alternative Embodiment

For Wireless Power Transfer (WPT) systems of the type described herein,there is also a need for a secure, unambiguous point-to-point,low-latency, full-duplex link between ground side charging system andvehicle side charging electronics. The communications link needs tosupport Battery Management System (BMS) commands and othercommunications scenarios between ground and vehicular electronics.

Supported operational scenarios include static and dynamic chargingunder various weather conditions in domestic and international markets.An inductively coupled communications system (ICCS) is reliable incongested radio environments with both licensed and unlicensedco-channel users while at the same time causing minimal interference.This same inductive communications system is also designed to functionthough standing water, snow, and ice.

In one embodiment, the narrowband full duplex, low latency, near-fielddata link for control of a resonant induction, wireless power transfersystem is augmented or replaced by a wideband full duplex, low latency,near field data link between the ground side assembly (GA) and vehicleside assembly (VA). This improved (hybrid or wideband) wireless duplexdata link allows for greater security, higher data rates, dynamicbandwidth selection, frequency agility, and modulation scheme agility tomeet local spectrum regulations, electric-and-magnetic fields (EMFs)safety, and data rate requirements for use in a near-field inductivecoupling communications system.

To support the widest possible static deployment configurations, thedatalink should be tolerant of interference generated by neighboring orproximate ground-side assembly emplacements. Proximate installations areattenuated either in distance (either geographically or in the case ofparking garages, vertically) or by a shielding structure (for instanceby curbs or floors as in parking garages). Neighboring systems may besited in the next vehicle parking spot or lane. In some neighboringcases, multiple clustered ground assemblies may be deployed in the sameparking spot or lane serve vehicles equipped with correspondinglyclustered vehicle assemblies in a matching geometry. Adjacentdeployments, where a “macro” GA is constructed of multiple, smallerclustered GAs are possible.

In dynamic charging deployment configurations, for instance in aGA-equipped travel lane, the datalink should be tolerant of interferencegenerated by neighboring or proximate ground-side assembly emplacementas well as supporting a soft-handoff capability between successiveground-side assemblies or ground-side assembly clusters. In asoft-handoff, the vehicle's charging platform would support multipledatalinks to successive ground assemblies in sequence as it moves in theGA-equipped travel lane.

Clustered Charger Scenario

A modular coil design, where a single coil assembly may be deployed as astandalone Ground Assembly (GA) and where two or more coil assembliesmay be clustered to achieve a larger (geometrically) Ground Assemblycapable of higher power transfer, is advantageous in tailoring a WPTsystem to user needs. For example, in the case of a bus, truck, train,construction equipment, or any other vehicle that requires wirelesspower transfer necessitating a clustered ground side assembly andcorresponding vehicle side assembly (VA) that are mounted locatedimmediately adjacent to one another (e.g., a bus with a VA consisting of4 adjacently mounted 50 kW charging coils with each coil assembly havingits own duplex inductive communications), there is a need to mitigateinterference of one coil's communication signals with the adjacentcoil's communication signals.

With this deployment flexibility, the vehicle may have one, two or morevehicle assemblies mounted to allow higher power transfer than may beachieved with a single VA. Similarly, the ground assemblies (GAs) may beclustered together and selectively enabled to match the geometry of theVA installation. In such clustered deployments, where single GAs areinstalled in a tight, contiguous fashion to form a single, macro GA; theintrinsic advantage of the near-field datalinks in not interfering withother datalinks in proximity due to the inherent radiated power falloffrange limitation is impacted. The magnetic field strength and magneticfield power drop at rates of 1/(r³) and 1/(r⁶) respectively (wherer=radius) for the inductive communications link in the near field.

Although the far-field radiated magnetic field from the antenna fallsoff only as 1/r for magnetic field strength and 1/r² for magnetic fieldenergy, the magnetic near-field is dominant for distances up to aboutλ/2π. For example, the radiation resistance of the magnetic inductionNear Field transmission antenna at 13.56 MHz is very small compared toits reactive impedance (typical ratio is smaller than 0.0005), as thevast majority of energy is coupled in the near field. Therefore, thepropagated energy in the far-field of the magnetic signal is negligiblecompared to that of an equivalent intentionally radiating system. Thisstrong drop-off of the field with distance means that although care istaken in dealing with signals from adjacent coils of the same clusteredcoil assembly, there is no concern of interference between coils ofadjacent vehicles or charging stations.

FIG. 10 illustrates an example of a clustered deployment in a sampleembodiment. In this case, the vehicle (e.g. a bus) 1001 has beenoutfitted with a clustered vehicle assembly 1004 mounted to theunderside of the vehicle 1001. As illustrated, a passenger stop orparking spot 1003 also has been equipped with the corresponding clusterdeployed ground assembly 1002.

FIG. 11a illustrates the signaling and components used by the WirelessPower Transfer (WPT) system's inductively coupled communications system(ICCS) 1101 in sample embodiments. FIG. 11a illustrates the ICCS 1101cross-sectionally whereby the Vehicle Assembly (VA) 1102 and GroundAssembly (GA) 1103 are shown as vertically opposed. Other deploymentoptions, for instance, a horizontal mounting with the VA 1102 on theside of a railcar and a GA 1103 mounted on a wall is possible. AnyGA-to-VA orientation in a deployment may be made as long as closeparallel opposition between the VA and GA is achievable. The VA 1102communications components include at least a pair of receive antennas1104 and 1106 located on the periphery of a single transmit antenna1105. The VA receive antennas 1104 and 1106 receive the transmission1110 and 1111 from the GA transmission antenna 1108. Similarly, the GAreceive antennas 1107 and 1109 receive the transmitted signal 1112 and1113. The bidirectional charging signal 1114 or 1127 may be present atany time during a communications session.

Additional near-field receiver antennas may be deployed to assist insignal reception and improve the collateral capabilities provided by thefull duplex communications system.

FIG. 11b shows an exemplary electric vehicle 1115 from beneath. In oneembodiment, additional receiver antennas may be emplaced on or withinthe VA 1102. With at least two antennas on the x-axis (front-to-back)and at least two antennas on the y-axis (left-to-right) the VA 1102would be enabled to determine GA coil alignment displacements along bothof the x and y axes. Preferentially, these VA-mounted receiver antennas1116, 1117, 1118, and 1119 would be placed on the four corners of the VA1102, within the range of the magnetically coupled GA transmitter's 1108signal 1112 and 1113. The VA coil assembly 1126 for transmission andreception of the bidirectional charging signal 1114 and 1127 alsoresides in the VA 1102 nominally under the transmission antenna 1105 ofthe VA 1102. The GA (not shown) architecture replicates thecommunications antennas and charging coil assembly to mirror those ofthe VA 1102 to enable duplex communications and bi-directional charging.

Note that additional diversity receiver antennas may also be locatedanywhere on the vehicle, preferentially displaced as far as possiblealong the length and width of the vehicle forming a secondarydistributed antenna/receiver system 1121, 1122, 1124, and 1125. Due tothe range from the GA-based transmitter from the distributed antennas1121, 1122, 1124, and 1125, the receiver antenna could be eithermagnetic inductive loops or near-field antennas as dictated by thereactive near-field range and radiative near field (aka the Fresnelregion) range of the GA transmitter's 1108 signal 1112 and 1113. In someembodiments, the displaced diversity receive antennas may bemagnetically coupled by either co-planar, parallel, or orthogonal (tothe transmitter loop antenna) mounted loop antenna dependent on rangefrom the magnetic transmission antenna(s). A hybrid loop antenna, withone loop element parallel to the transmitter loop and a second loopelement set orthogonal may also be used to extend the magneticallycoupled link in cases where transmitter-to-antenna range or the abilityfor a co-planar mounting is uncertain.

In the dynamic charging case, a distributed forward antenna or antennas1121 and 1122 allow for increased communication range enablingcommunication with GAs forward of the current GA. This advancedcommunication enables GA in the path of the vehicle power-up time priorto need to minimize ramp-up. The distributed lateral antennas right 1122and 1124 and left 1121 and 1125 also provide for centering alignment inthe direction of travel to maximize coil efficiency.

In one physical embodiment, four or more receiver antennas 1116, 1117,1118, and 1119 are distributed on the VA 1102 in anterior and posterior(in relation to the forward direction of travel) fashion and on theright and left transverse fashion. Four additional antennas 1121, 1122,1124, and 1125 are added with 2 affixed to the front 1120 (e.g. in thebumper, under the bumper, or on the vehicle frame) and 2 on the rear1123 similarly affixed or embedded. In both the front and reardeployments, the antennas should have maximum possible separation to theleft and right on the transverse axis.

The distributed antennas can be backhauled to the ICCS 1101 using eitherwired or wireless (e.g. Bluetooth, Zigbee (IEEE 802.15)) connections.The ICCS 1101 will compensate for the differing reception and processingtime needed for the communications link method and data protocol used.

The distributed antennas 1121,1122,1124, and 1125 with a common or knownoffset to the horizontal plane also enable increased alignmentcapability. With diversity receivers, positioning and ranging techniquessuch as Signal-Strength-Measurement (SSM), Time-of-Arrival (TOA), andTime-Difference-of-Arrival (TDOA) become available. Use of a directionalreceiver antenna would enable the Angle-of-Arrival (AoA) technique. Thefront-of-vehicle-mounted directional antennas with the AoA technique isespecially advantageous for positioning and alignment in the forwarddirection.

An Intelligent Transport System's (ITS) permanent 79 GHz band allocationfacilitates use of, TOA, TDOA, AOA, or hybrid positioning using two ormore of the described techniques. The twelve ITU (InternationalTelecommunication Union) defined Industrial, Scientific and Medical(ISM) bands are another potential spectrum for use in alignment (6 areglobally available, the other 6 ISM bands may be available dependent onlocal regulations). Alignment precision will vary with the use of higherfrequencies providing greater resolution and lower frequencies providinglower resolution.

Use of the distributed antennas with the TDOA, AOA, or TDOA-AOA hybridpositioning techniques can be used in the generation of a Z-Axis(vertical) measurement. In some embodiments, non-radio means, forexample an ultrasonic transducer range-finder could be used for Z-axisestimation.

Alternately, if a vehicle is not properly equipped, the nominal Z-Gapfor the make, model, manufacturer, and variant could be uploaded eitherfrom the vehicle or a landside networked server for use in setting theWireless Power Transfer GA voltage and coil enablement in the coilcluster.

Software Defined Radio

One option for implementation of the improved ICCS 1101 is by use ofsoftware-defined transmitters and receivers to improve the signalingbetween the ground station and vehicle installation using the inductivecoupling communication between the ground side assembly (GA) 1103 andvehicle side assembly (VA) 1102.

The ICCS 1101 is designed in sample embodiments to be selectable amongtwo or more types of circuitry for amplitude modulation, phasemodulation, and frequency modulation, as well as circuitry enabling useof spreading techniques such as direct sequence spread spectrum andChirp spread spectrum (CSS) (e.g. binary orthogonal keying (BOK),frequency hopping, and direct modulation (DM)) as necessary. Asdescribed below, such features may be implemented in a fieldprogrammable gate array (FPGA) in sample embodiments, although thedescribed functionality may also be deployed using discrete integratedcircuit components and/or multichip modules and/or in software executedby other processing devices such as a digital signal processor (DSP). Insome embodiments, the ICCS 1101 may use multiple simultaneoussubcarriers as in an Orthogonal Frequency Division Multiplex system(OFDM) wherein the subcarriers may be assigned to unlicensed spectrum(or reserved spectrum) and use any of the modulation schemes described.

FIG. 12a illustrates the functional elements of the ICCS in sampleembodiments. As illustrated, a receiver 1201 uses an antenna or antennasspecialized for magnetic inductive signaling. The received analog signalmay be filtered in the receiver 1201 as described above. The receivedsignals are processed by digitization elements 1202 to take the receivedanalog signal and convert it into a digital representation of thesignal. The digital representation of the received signal is thendigitally processed by processing element 1203. Data extracted from theprocessed signal is then output via a digital interface 1206.

Incoming digital data also may be applied to the processing element 1203via an input interface 1207. The incoming data is packaged by theprocessing element 1203 prior to conversion to an analog signal in theanalog conversion element 1204. Once in analog form, the signal can thenbe filtered and transmitted by transmitter 1205 via an antenna orantennas specialized for magnetic inductive signaling.

In sample embodiments, the ICCS functional elements of FIG. 12a may beimplemented in any of a number of ways. For example, the ICCS may beconfigured as:

-   -   a circuit comprised of discrete integrated circuits (ICs) (e.g.,        an analog to digital converter (ADC), a digital to analog        converter (DAC)) with programmable elements (e.g., a field        programmable gate arrays (FPGAs), EEPROMs, etc.);    -   as mixed hardware (ICs), software, and embedded firmware in a        multi-chip module;    -   as firmware residing in an        application-specific-integrated-circuit (ASIC) that contains the        needed control logic, digitization and analog conversion        function; and    -   as software structures running on a computing platform (e.g., a        central processing unit (CPU) or digital signal processor (DSP))        with attendant digital to analog and analog to digital        circuitry.

In each case, analog signal filtering may be included as necessary forthe design selected (e.g., for super-heterodyne designs with bandpassintermediate frequency (IF) stages or direct conversion designs withlimited analog bandwidths).

Election of which ICCS implementation (FPGA vs. DSP) and deployment (asan assembly of Discrete ICs, multi-chip IC module, or ASIC) to use ishighly dependent on development costs, production volumes, and cost ofcomputing resources with the necessary. In implementations, the FPGAoffers parallel path signal processing while the CPU/DSP offers superiormemory access and an operating system to simplify tasking. The discreteIC packaging gives the most flexibility in selecting components andplacement of those components, while the multi-chip module offers fixedinterconnections between discrete components. The ASIC package offers inboth ICCS components and interconnections into a single integratedsubsystem at the highest development time and cost, but the simplest todeploy. In sample embodiments, the ICCS configuration is selected at thetime of manufacturing but may also be user selectable during use.

FIG. 12b illustrates a sample embodiment of the ICCS 1101 including theVA 1202 and GA 1201 in a discrete integrated circuit embodiment. Asillustrated, the communication channels 1211 and 1227 use magneticinduction coupling with minimally propagating magnetic fields for theshort-range, low-power magnetic field link between the GA 1260 and VA1261. The GA communication signal 1211 and the VA communication signal1227 may either be narrowband or wideband depending on the presetprogramming, the stage of the charging cycle (approach, roughpositioning, fine positioning, Foreign-Object-Detection (FOD) andLive-Object-Detection (LOD) scanning, charging, charging termination),or whether a threshold of signal quality (e.g. received signal strength,Bit-error-rate) has been crossed.

The core 1262 of the GA inductively coupled communications system 1260includes a Field Programmable Gate Array (FPGA) 1265, anAnalog-to-Digital-Converter (ADC) 1263, and aDigital-to-Analog-Converter (DAC) 1264. The FPGA 1265 supplies thecomputation resources. Computational operations by the FPGA 1265 includesignal processing (e.g. signal summation, combination, and selection;modulation, demodulation, digital filtering, data extraction, automaticgain control (AGC), and ICCS hardware control). Data from the GA andexternal systems are input into the GA core 1262 via a digital interface1240 for processing for transmission to the VA 1261.

The GA core Digital-to-Analog Converter (DAC) 1264 serves to transformthe FPGA's digital output bit stream into a quantized analog signalbefore being amplified by the transmit amplifier 1208 and then beingband-limited and smoothed by the bandpass filter 1209 and transmitted bythe GA transmit antenna 1210, which propagates as the inductive magneticsignal 1211.

The GA communication's signal 1211 crosses the air gap 1266 between theVA 1261 and GA 1260 and is then received at the VA receiver antennas1212 and 1213 (note that in this example, two receiver antennas areused, but the design supports use of a single receiver antenna and anyplurality of receiver antennas). Once received by one or more of theVA's paired coupling antenna structures 1212 and 1213, the GA signal isthen bandpass-filtered using filters 1214 and 1215. The band-limitedsignals are then amplified by the pair of low-noise-amplifiers (LNAs)1216 and 1217, one for each VA receiver path. A second pair of bandpassfilters 1218 and 1219 are then used to limit the signal frequencybandwidth for direct digital conversion on each of the VA receive paths.

The analog-to-digital conversion takes place at the VA ADC 1223. The VAADC 1223 may be implemented either as a paired set of ADCs or as ann-channel ADC (depending on the number of receive antennas used). Thedigitized signal is then passed to the VA FPGA 1222. The VA FPGA 1222converts the received digitized signals using conventional DigitalSignal Processing techniques and then processes the reconstructed bitstream (e.g. removing the framing, training sequences, implementing theforward error correction and data encoding (e.g. coding from usingconvolutional coding, turbo coding, Hamming Codes), decodingsecurity-masked bit sequences) and delivers the bit stream via a digitalinterface 1238 to the Vehicle Battery Management System (VBMS) 1239,potentially thru intermediary processors, networks, and protocols suchas the Controller Area Network (CAN bus) (not shown). Measurementsrelated to the communications signals are output on a digital interface1236 to vehicle-based processor 1250. Measurements related to thecharging signal are output on a digital interface 1237.

The Vehicle Battery Management System (VBMS) 1239, the Vehicle'sOccupant information system, the Vehicle's entertainment system, andother vehicle-borne data or telemetry systems provide a bit stream tothe VA FPGA 1222 via the digital interfaces 1238 and 1243 dependent onthe configuration of the VBMS and vehicle on-board systems. The VA FPGA1222 applies the framing, training sequences, implementing the forwarderror correction and data encoding (e.g. using convolutional coding,Hamming Codes, Hadamard code), encoding security-masked bit sequences)and delivers the bit stream to the VA Digital-to-Analog-Converter (DAC)1221. The output of the VA DAC 1221 is then amplified by a transmitamplifier 1224. The VA signal for transmission is then filtered by abandpass filter 1225 to match the desired channel bandwidth. Theband-limited analog VA signal is then transmitted using a couplingantenna structure 1226 over the magnetic field air interface 1266.

The VA's inductive magnetic signal 1227 is received by one or more ofthe GA's coupling antenna structures 1228 and 1229. The VA signal isthen bandpass filtered on each GA receive path using filters 1230 and1231. The band-limited signals are then each amplified by the pair oflow-noise-amplifiers (LNAs) 1232 and 1233, one for each GA receiverpath. A second pair of bandpass receivers 1234 and 1235 are then used tolimit the signal frequency band for direct digital conversion on each ofthe GA receive paths. In some configurations of the ICCS, the band passfilters 1209, 1214, 1215, 1218, 1219, 1225, 1230, 1231, 1234, and 1235may be constructed as a switched filter bank to accommodate multiplefrequency bands.

The analog-to-digital conversion takes place at the GA ADC 1263. The GAADC 1263 may be implemented either as a paired set of ADCs or as atwo-channel ADC. The digitized signal is then passed to the VA FPGA1265. The VA FPGA 1265 converts the received digitized signals usingconventional Digital Signal Processing techniques and then processes thereconstructed bit stream (e.g. removing the framing, training sequences,implementing the forward error correction and data encoding (e.g. usingconvolutional coding, turbo coding, Hamming Codes), decodingsecurity-masked bit sequences) and delivers the bit stream toground-side computation resources 1241 local to the wireless charger andexternal communications interfaces 1242, potentially thru intermediaryprocessors, interfaces, and protocols (not shown). In case of a detected(by the GA) or transmitted (by the VA) failure event, the GA FPGA 1265signals the Emergency Shut-off 1244 (e.g. in the event of a coil failureor thermal threshold exceeded) which disables the charging signal 1245.

Closed and Open Loop Control and Reporting

The ICCS 1101 actively measures both the charging signal 1245 andcommunication signals 1211 and 1227. Measurements may include receivedsignal strength, bit-error-rate, sum and difference of the signal 1227as received by the first 1228 and second 1229 antenna structures, Eb/No(ratio of Energy per Bit (Eb) to the Spectral Noise Density (No)),received signal strength indication (RSSI), center frequency, andamplitude and phase shift at the first and second receive antennas 1228and 1229. The measurements may be delivered via the GA digital controlinterface 1241 to ground or the VA digital control interface 1236 forone or more vehicle-based processors 1250 for alignment detection, andclosed loop charging system management and control.

The closed loop control may include providing to the FPGA 1222 nearreal-time voltage and current measurements (on VA), VA thermalmeasurements, Z-gap changes due to loading or unloading of the vehicle,soft VA or GA failure (clustered) alerts, alerting of mid-chargingperformance events, and conveyance of additional sensing on vehicle siderelated to the VA or vehicle electrical system to the GA and VA asneeded.

The VBMS 1239 uses the VA control digital interface 1238 to passcommands for transmission to the charging system which may command theGA via the GA control digital interface 1241.

Spread Spectrum Wideband Signal

In one embodiment, the wideband signal used for the full duplex VA-GAcommunications link is an asynchronous direct sequence spread spectrumsignal using complementary code sequences. In some deployment scenarios,e.g. in cases where GAs are deployed adjacently as components of alarger macro-GA cluster (for instance as a single vehicle parking spotcharger), distance cannot be relied on to provide sufficient magneticsignal attenuation to mitigate co-channel interference between themultiple GA-to-VA and VA-to-GA transmissions. The use of spread sequencetechniques allow for each of the GA and VA receivers to distinguishbetween signals sent for each receiver and co-channel interference. Theuse of complementary codes in a direct sequence spread spectrum systemare used to allow correlation processing by the receivers to overcomethe co-channel interference and lack of synchronization betweentransmitters of both the GA and the VA.

With sufficient distance between GAs (and paired VAs), signalattenuation of the magnetic signals permit code reuse which in turnallows for shorter code sequences. With shorter code sequences, thenumber of ‘chips’ per bit in the direct sequence spread spectrum systemcan be minimized resulting in greater data rates over the samebandwidth.

In a communications system using inductive coupling for transmissions,signal reflection and multipath are minimized by the innate physics ofmagnetic field propagation. In one embodiment, direct sequence codespreading using complementary code sequences is designed to mitigateco-channel interference between closely sited (clustered, adjacent orproximate) transmitters and receivers such as in a wireless chargingparking lot or lane.

Use of an asynchronous system allows multiple, individual GroundAssemblies, each with its own transmitter and receiver, to be deployedin adjacent or proximate fashion without need a shared real-time timingsource. The lack of need for a common timing source removes the need forclock recovery and/or phase locking between the GA and VA systems. Eachaligned GA and VA pair thus may communicate independently regardless ofthe deployed number of units or the number of units functional. If a GAis unpaired with a VA (due to differing deployment geometries or VAfailure conditions) that GA will not initiate a charging signal.

In sample embodiments, such a charging system may be used to charge avehicle by positioning the VA of the vehicle with respect to the GA soas to receive a charging signal. The coils of the GA and the VA areselectively enabled based on geometric positioning of the VA relative tothe GA for charging so that only the aligned coils are activated. Asappropriate, one or both of the transmit/receive systems of the GA andVA are selected to have a same type of signal processing circuitry. Thetransmit/receive systems may then then be used to communicate chargingmanagement and control data between the transmit/receive systems of theGA and VA over inductive links during charging.

As noted above, the transmit/receive systems may include hardware,software, and/or firmware that provide one or more of amplitudemodulation, phase modulation, frequency modulation, Orthogonal FrequencyDivision Multiplexing (OFDM), and spread spectrum that implementstechniques including at least one of direct sequence spread spectrum,Chirp spread spectrum (CSS), binary orthogonal keying (BOK), frequencyhopping, and direct modulation (DM). The types of transmit/receivesystems are selected to be the same at design/manufacturing time or byuser selection, for example. The VA and GA may then communicate softwareupdates, diagnostic or telemetry information, and/or passengerentertainment services data therebetween during charging.

FIG. 13a illustrates an overhead view of a parking lot based wirelesscharging station deployed in a single-row geographic arrangement 1301 ina sample embodiment. The parking spots 1304, 1305, 1306, and 1307 aredefined by the curb 1303 and painted line marker as is typical. A travellane 1302 provides vehicle access to each parking spot. In this example,each parking spot 1304, 1305, 1306, and 1307 has a wireless chargingground assembly (GA) 1310, 1311, 1312, and 1313 installed. The GAs 1310,1311, 1312, and 1313 are shown as clustered assemblies of four adjacent,independent GAs, although other geometries are possible to the lengthand width of the parking stall.

The active GAs 1311, 1312, and 1313 radiate a magnetic communicationssignal 1315 before and during each charging session. Due to thepropagation characteristics of a coupled magnetic induction signal andvertical antenna orientation, co-channel interference is limited towithin GA clusters and potentially between neighboring parking stalls1314.

The magnetic signal radiated by each active GA cluster 1311, 1312, and1313 is one source of co-channel interference for each (in this examplethere are up to 8 signals per cluster, 4 from GA to VA and 4 from VA toGA when active) communications link. Potential overlap or impingement ofmagnetic signals 1315 from a nearby active GA 1312 or 1313 equippedparking spots is also possible, but with sufficient physical separation1309 between non-neighboring active GAs 1311 and 1312 serving to vastlyreduce or eliminate potential co-channel interference. Possibleadditional chargers across the travel lane 1302 will have sufficientphysical separation 1308 to limit co-channel interference potential.

FIG. 13b illustrates an overhead view of a parking lot based wirelesscharging station deployed in a double-row geographic arrangement 1316 ina sample embodiment. The double row 1316 of GA equipped parking isisolated by travel lanes 1304. In this illustration, parking spots 1317,1320, 1321, and 1322 have currently active GAs while parking spots 1318,1319, 1323, and 1324 are non-active (i.e., in a non-charging state,parking spots may be unoccupied, or occupied but with charging that isnon-operational, terminated, or not yet started). Potential co-channelinterference of the magnetically coupled full duplex communicationssystem is present in the active parking stalls (those that radiate amagnetic signal 1315). Co-channel interference between each of thecluster of GAs in a macro GA (here the macro GA consists of 4 adjacentGAs each with independent duplex communications) and potentialco-channel interference 1314 between neighboring macro GAs is toleratedby the communications system. Same row nearest active GAs 1317 and 1320or across row active nearest GAs 1322 and 1320 with sufficientgeographic isolation 1309 are not potential interferers as are possibleGAs geographically distanced 1308 across the one or more travel lanes1304 that provide access to the double row charging station 1316.

Enabled Communication Links

In one embodiment, during the charging cycle, the full duplex link isalways enabled, providing continuous communications between the VA andGA as well as a secure conveyance for vehicle software updates,diagnostics, telemetry, entertainment, and other information. The ICCS1101 supports changes in transmission and reception frequencies,modulation and coding to support specific events prior to, during andafter a charging session.

In clustered deployments, each individual GA may support an independentcommunications link with each individual VA. In this way, a clustered GAmay support a lone VA or clustered VA (e.g. 1 row of 2 VAs; 2 rows of 2VAs; 3 rows of 2 VAs; and so on up to the maximum width and length ofthe vehicle) or even a partially operative VA by only activating thecharging signal for GAs with geometrically corresponding VAs. Use ofindependent communications eases both deployment and operations as asingle charging site may support multiply configured vehicles.Alternatively, the GAs may be deployed as a coordinated cluster whereonce the charging signal is activated a single GA and VA maintaincommunications.

Static Case

The duplex communication datalink serves to provide authentication andaccess control for the WPT in static and dynamic charging scenarios.Additionally, the datalink may be used to provide information, softwareupdates, diagnostic or telemetry information and passenger entertainmentservices between the GA and VA. The continuous nature of the duplexdatalink results in faster feedback for control systems such asdeactivation of the charging signal after the detection of foreignmaterial being introduced between the VA and GA. The location of thecommunications system receivers on the physical periphery of thecharging coil also allows earliest detection of an introducedobstruction.

Dynamic Case

In an embodiment of the dynamic charging case, the communications linkis maintained as the vehicle moves down an equipped railway or highway.In this deployment, using the ICCS enabled with Direct SequenceSpreading System (DSSS), code sequences are selected to be as short andas orthogonal as possible with adjacent GAs allowing for fastsoft-handoff between GAs. Using the magnetic induction communicationslink, the expected sequence of GAs and associated code sequences may beuploaded to the vehicle to increase allowable velocity on a GA-equippedtravel lane or railway. Using the uploaded sequence, the ICCS may bepreloaded to demodulate and decode the communications signal faster.

FIG. 14 illustrates one example of highway 1401 enabled for dynamiccharging. The highway is set between two curbs 1402 and 1403 and dividedinto travel lanes 1405 and a charging lane 1406. These charging lanesmay have set speeds and set inter-vehicle gap lengths to better optimizecharging. The charging lane speed is set to manage charging time (akadwell time) on each sequential GA 1407. Vehicles 1404 and 1409 may moveinto the charging lane, shown here with distinct lane markings orphysical separation 1408, either at will or at designated entry points.

In a railway example, a sequence or array (sequential clusters) of GAsfor charging VA-equipped railcars is placed between the tracks (up toone gauge wide). The GAs also could be facing VAs deployed on theside(s) or on top of the railcar.

By having a plurality of GAs arrayed in sequence along a travel path,customization of the GA may be deployed such as longer antenna (bothcharging and communications) and providing autonomous vehicle controlinformation for optimal charging both at the present lane and potentialcharger sites along potential routes.

Independent Communications Paths per Assembly

In one embodiment, a full duplex inductively coupled datalink isdeployed for each member of a cluster of independent GAs (a macro GA).Similarly, each independent VA (part of a macro-VA cluster) is equippedwith a full duplex inductively coupled datalink.

This independent operation of datalinks gives the lowest latencycommunications by removing the circuitry and processing needed tocoordinate communications between assemblies when assemblies areclustered. The lack of coordination also means the link initiation isfaster since concurrent datalink setup by each assembly pair (GA-to-VA)is enabled.

The independent datalinks also ease deployment of single and multipleassemblies. Geometrically arbitrary clusters of GAs are deployable inwhatever area or patterns are needed to support vehicle dimensions andscale power supply needs.

By making each VA and GA functionally identical (e.g. with identicalmagnetic induction antenna and a common resonant induction coil unit),economies of scale may be realized. The common resonant induction coilunit also serves to increase efficiency of the charging signal and thusthe power efficiency of the ICCS as a whole.

The independent nature of the paired GA-to-VA configuration means that asingle GA or VA failure in a clustered deployment is a gracefuldegradation to a lower charging state via the remaining GA-VA pairs. Inone aspect, the failure of a VA unit results in the immediate cut-off ofthe charging signal from the paired GA. Since this GA is no longerradiating, the vehicle is not subject to heating from a no-longerterminated charging signal.

Those skilled in the art will appreciate that the topology and circuitimplementation methodology described herein enables effectiverealization as a single application specific integrated circuit,discrete integrated circuits, multichip modules, and/or as softwareexecuted on a digital signal processing circuit with ancillary A/D andD/A circuitry. Further, while the disclosure contained herein pertainsto the provision of electrical power to vehicles, it should beunderstood that this is only one of many possible applications, andother embodiments including non-vehicular applications are possible. Forexample, those skilled in the art will appreciate that there arenumerous applications of providing a full duplex data link innon-vehicle inductive charging applications such as portable consumerelectronic device chargers, such as those (e.g., PowerMat™) used tocharge toothbrushes, cellular telephones, and other devices. Inaddition, those skilled in the art will appreciate that the transmissionbandwidth (data rate) of the communications system described herein maybe increased using simultaneous amplitude and angle modulation usingother complex modulation methods and by use of multiple modulatedforward and reverse path carriers. Accordingly, these and other suchapplications are included within the scope of the following claims.

What is claimed:
 1. A charging system comprising: a first coil assemblycomprising a charging coil and a first full duplex inductively coupleddata communications system comprising a first transmit/receive systemthat transmits a first signal over a first inductive link and receives asecond signal over a second inductive link; and a second coil assemblycomprising a charging coil and a second full duplex inductively coupleddata communication system comprising a second transmit/receive systemthat receives the first signal over the first inductive link andtransmits the second signal over the second inductive link, wherein thefirst and second transmit/receive systems are adapted to be selectableamong at least one of hardware, software, or firmware configurationsthat are adapted to modulate output signals and to demodulate inputsignals, and wherein the charging coil of the first coil assembly isconfigured to be disposed in parallel to the charging coil of the secondcoil assembly to receive a charging signal during charging and isselectively enabled to match a geometry of the second coil assemblyduring charging.
 2. A charging system as in claim 1, wherein the firsttransmit/receive system comprises a processor that processes data fromat least one of the first coil assembly or external systems fortransmission to the second coil assembly and processes data receivedfrom the second coil assembly for delivery to at least one of the firstcoil assembly or the external systems for processing.
 3. A chargingsystem as in claim 2, wherein when a failure event is detected by thefirst coil assembly or received from the second coil assembly, theprocessor disables the charging signal.
 4. A charging system as in claim1, wherein the second transmit/receive system comprises a processor thatprocesses at least one of commands or data from at least one of thesecond coil assembly or external systems for transmission to the firstcoil assembly and processes data received from the first coil assemblyfor delivery to at least one of the second coil assembly or at least oneof the external systems.
 5. A charging system as in claim 4, wherein thesecond coil assembly further comprises a digital interface, and theprocessor provides measurements related to the first signal, the secondsignal, and the charging signal to the digital interface.
 6. A chargingsystem as in claim 5, wherein the measurements include at least one ofsignal strength, bit-error-rate, ratio of Energy per Bit to a SpectralNoise Density, frequency, or amplitude and phase shift at first andsecond antenna structures of the first coil assembly and second coilassembly.
 7. A charging system as in claim 6, wherein the externalsystems comprise an external processor, wherein the measurements aredelivered via the digital interface to the external processor for atleast one of alignment detection or closed loop charging systemmanagement and control.
 8. A charging system as in claim 7, wherein theexternal processor provides at least one of near real-time voltage andcurrent measurements of the second coil assembly, thermal measurementsof the second coil assembly, Z-gap changes, first coil assembly orsecond coil assembly failure alerts, alerts regarding mid-chargingperformance events, or additional sensing data related to the secondcoil assembly to the processor for transmission.
 9. A charging system asin claim 1, wherein the first signal and the second signal areconfigured as either narrowband or wideband signals depending on a stageof a charging cycle or whether a threshold of signal quality has beencrossed.
 10. A charging system as in claim 1, wherein the first signaland the second signal are configured as an asynchronous spread spectrumsignal.
 11. A charging system as in claim 10, wherein the first andsecond transmit and receive systems each comprise a direct sequencespread spectrum system that transmits code sequences that allow for thefirst and second transmit/receive systems to distinguish between signalsand co-channel interference.
 12. A charging system as in claim 11,wherein the code sequences are complementary code sequences.
 13. Acharging system as in claim 1, wherein the at least one of hardware,software, or firmware are adapted to modulate the output signals usingat least two of amplitude modulation, phase modulation, frequencymodulation, Orthogonal Frequency Division Multiplexing (OFDM), or spreadspectrum techniques.
 14. A charging system as in claim 13, wherein thespread spectrum techniques comprise at least one of direct sequencespread spectrum, Chirp Spread Spectrum (CSS), binary orthogonal keying(BOK), or frequency hopping.
 15. A charging system as in claim 1,wherein the first and second transmit/receive systems each comprises areceiver, an analog to digital converter, a digital processor thatprocesses data from at least one of the first coil assembly or externalsystems for transmission to the second coil assembly and processes datareceived from the second coil assembly for delivery to at least one ofthe first coil assembly and the external systems for processing, adigital to analog converter, or a transmitter.
 16. A charging system asin claim 15, wherein the analog to digital converter and digital toanalog converter are implemented as discrete integrated circuits and thedigital processor is implemented as a field programmable gate array. 17.A charging system as in claim 15, wherein the analog to digitalconverter, digital processor, and digital to analog converter areimplemented as firmware residing in anapplication-specific-integrated-circuit (ASIC).
 18. A charging system asin claim 15, wherein the digital processor of each transmit/receivesystem processes input data for transmission and processes data receivedfrom the other transmit/receive system using software structuresimplemented on the digital processor.
 19. A charging system as in claim15, wherein the first and second transmit/receive systems each furthercomprises at least one bandpass filter.
 20. A method of charging avehicle comprising: positioning a vehicle assembly with respect to aground assembly so as to receive a charging signal, the vehicle assemblycomprising one or more charging coils, with each charging coil having afirst full duplex inductively coupled data communication systemcomprising a first transmit/receive system that receives a first signalover a first inductive link and transmits a second signal over a secondinductive link, and the ground assembly comprising one or more chargingcoils, with each charging coil having a second full duplex inductivelycoupled data communications system comprising a second transmit/receivesystem that transmits the first signal over the first inductive link andreceives the second signal over the second inductive link; selectivelyenabling the charging coils of the ground assembly and the vehicleassembly based on geometric positioning of the vehicle assembly relativeto the ground assembly for charging; and communicating chargingmanagement and control data between the first and secondtransmit/receive systems over the first and second inductive linksduring charging.
 21. A method as in claim 20, further comprisingconfiguring the first transmit/receive system and the secondtransmit/receive system to have a same type of at least one of hardware,software, or firmware adapted to modulate the output signals using atleast two of amplitude modulation, phase modulation, frequencymodulation, Orthogonal Frequency Division Multiplexing (OFDM), or spreadspectrum techniques.
 22. A method as in claim 21, wherein the spreadspectrum techniques comprise at least one of direct sequence spreadspectrum, Chirp Spread Spectrum (CSS), binary orthogonal keying (BOK),or frequency hopping.
 23. A method as in claim 20, further comprisingcommunicating at least one of software updates, diagnostic or telemetryinformation, or passenger entertainment services data between the groundassembly and the vehicle assembly via the first and second inductivelinks during charging.
 24. A method as in claim 20, further comprisingdisabling the charging signal when a failure event is detected by theground assembly or received from the vehicle assembly.
 25. A method asin claim 20, further comprising the first transmit/receive systemprocessing at least one of commands or data from at least one of thevehicle assembly or from external systems for transmission to the groundassembly and processing data received from the ground assembly fordelivery to at least one of the vehicle assembly or at least one of theexternal systems.
 26. A method as in claim 25, further comprisingproviding measurements related to the first signal, the second signal,and the charging signal to a digital interface for processing.
 27. Amethod as in claim 26, wherein the measurements include at least one ofsignal strength, ratio of Energy per Bit to a Spectral Noise Density,frequency, or amplitude and phase shift at first and second antennastructures of the vehicle assembly and ground assembly.
 28. A method asin claim 27, further comprising delivering the measurements via thedigital interface to an external processor for at least one of alignmentdetection or closed loop charging system management and control.
 29. Amethod as in claim 28, further comprising transmitting at least one ofnear real-time voltage and current measurements on the vehicle assembly,thermal measurements of the vehicle assembly, Z-gap changes due toloading or unloading of a vehicle containing the vehicle assembly,ground assembly or vehicle assembly failure alerts, alerts regardingmid-charging performance events, or additional sensing data related tothe vehicle assembly from the vehicle assembly to the ground assembly.30. A method as in claim 20, further comprising configuring the firstsignal and the second signal as either narrowband or wideband signalsdepending on a stage of a charging cycle or whether a threshold ofsignal quality has been crossed.
 31. A method as in claim 20, furthercomprising configuring the first signal and the second signal as anasynchronous spread spectrum signal.
 32. A method as in claim 31,further comprising transmitting code sequences between the first andsecond transmit/receive systems that allow for the first and secondtransmit/receive systems to distinguish between signals and co-channelinterference.
 33. A method as in claim 32, wherein transmitting the codesequences comprises transmitting complementary code sequences.